About a month ago, my wife and I got a Maltipoo puppy from a breeder and at the same time my good friend and his fiance got my puppies sister. Right now they are 14 weeks old and they are the best of friends. My wife works 3 days a week (sometimes on weekends) so on the week days that my wife has to work, they get to play together all day. I am glad that my friend and I chose to get them together this way my Milo gets to grow up with his sister, always has a playmate, and I don't feel as bad leaving him to go to work (they play together anywhere from 1-3 times a week depending on my wifes work schedule..they play on the weekdays that my wife and I are both working). My question is...my dog is a male and my friends is a female and my dogs sister from the same litter. We ARE NOT BREEDING them and BOTH dogs WILL be fixed. My question is being that right now neither dog has been altered at what age do dogs become sexual? I fell kinda silly asking this but I just want to be careful. My wife and I are planning on getting Milo neutered next month and I assume his sister will be Spayed around the same time...It really depends on my wifes work schedule..I want her to be able to take the week off to nurse him in the day when he gets it done (not sure if this is necessary or not). So again my question is...at what age can a dog actually get pregnant? At what age do they actually mate? I just want to make sure they are both spayed and neutered prior to that time, because like I said above 1-3 days a week they are spending all day together. Thanks in advance.